Fluid cooled hub assembly for a contact wheel

ABSTRACT

A contact wheel hub assembly for a surface finishing machine is provided with cooling fluid conduits to remove heat generated by the contact wheel and a cooperating abrasive belt during grinding, sanding, buffing and similar finishing operations. The contact wheel of the assembly is composed of a rotatable support sleeve and a contact wheel tread over which the abrasive belt moves in driving contact. The support sleeve is provided with a plurality of axially extending internal grooves which serve as conduits for a cooling fluid supplied to the wheel during a finishing operation. The cooling fluid exhausts to the ambient environment through the grooves to remove heat generated by the finishing operation from the sleeve and contact wheel tread.

United States Patent [191 Fournier June 19, 1973 FLUID COOLED HUB ASSEMBLY FOR A CONTACT WHEEL [75] Inventor: Joseph L. Fournier, Andover, Conn.

22 Filed: Mar. 3, 1971 [21] Appl. No.: 120,600

Primary Examiner-Donald G. Kelly Att0rneyMcCormick, Paulding & Huber [57] ABSTRACT A contact wheel hub assembly for a surface finishing machine is provided with cooling fluid conduits to remove heat generated by the contact wheel and a cooperating abrasive belt during grinding, sanding, buffing and similar finishing operations. The contact wheel of the assembly is composed of a rotatable support sleeve and a contact wheel tread over which the abrasive belt moves in driving contact. The support sleeve is provided with a plurality of axially extending internal grooves which serve as conduits for a cooling fluid supplied to the wheel during a finishing operation. The cooling fluid exhausts to the ambient environment through the grooves to remove heat generated by the finishing operation from the sleeve and contact wheel tread.

6 Claims, 4 Drawing Figures FLUID COOLED llll UB ASSEMBLY FOR A CONTACT WHEEL BACKGROUND OF THE INVENTION This invention relates to the field of machine tools and, more particularly, is directed to grinding, sanding, buffing and similar surface finishing machines that employ an abrasive belt and contact wheel to perform the finishing operations.

Contact wheels of the type to which the present invention is directed have been in use for some time and are more commonly employed for finishing metal, plastie and wooden workpieces. The machine employing the contact wheel is composed generally of a frame, a drive motor mounted on the frame and an endless abrasive belt which is driven by the motor over one or more guide wheels or pulleys, including the contact wheel, mounted on the frame. In the finishing operation, the portion of the abrasive belt on the contact wheel is pressed against a workpiece while the belt is driven by the motor. The contact wheel has a resilient peripheral tread which is engaged by the inner surface of the abrasive belt so that the wheel is driven by the belt. When the portion of the belt on thecontact wheel is pressed against the workpiece, the belt is permitted to conform to the irregular contours of a workpiece due to the resilient character of the underlying tread and produces a desirable finish on the workpiece surface. In the finishing operation, the cyclic flexing of the tread at the region of contact between the belt and the workpiece and the friction between the abrasive belt and the workpiece produce substantial heat. This heat can raise the temperature at the bond between the tread and the support sleeve of the contact wheel to a level which destroys or at least weakens the bond. When the wheel is rotated at high speeds by the belt, the centrifugal forces applied to the tread break the weakened or damaged bond and the contact wheel fails.

It is accordingly desirable to provide a cooling arrangement for removing the heat generated in a contact wheel during a finishing operation.

SUMMARY OF THE INVENTION The present invention resides in a fluid cooled hub assembly adapted for mounting the resilient tread of a contact wheel. The hub assembly includes a rotatable support member having a generally cylindrical external mounting surface to which the tread of the contact wheel is secured. The mounting surface extends coaxially about the axis of rotation of the support member and a cooling fluid conduit extends in the axial direction along at least one portion of the support member beneath the external tread-mounting surface for transporting a cooling fluid adjacent the support member. The cooling fluid removes heat generated during a finishing operation and thereby prevents the temperature at the bond between the tread and support member from reaching a level at which the bond is weakened or destroyed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a belt-driven contact wheel and the supporting apparatus of a surface finishing machine embodying the present invention.

FIG. 2 is an end view of the contact wheel and the supporting hub assembly shown in FIG. I.

FIG. 3 is a sectional view of the contact wheel and the hub assembly taken along the section line 3-3 of FIG. 2.

FIG. 4 is a plan view of the support arm shown in FIG. 1 with the wheel mounting end of the arm in section.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a portion of a surface finishing machine, of the type described above, embodying the present invention. A fluid cooled contact wheel, generally designated 10, is supported for rotation at the projecting end of a support arm 12 which forms a portion of the frame of the finishing machine. An abrasive belt 14 extends over one region of the periphery of the wheel 10 and several other guide wheels (not shown) on the frame and is driven by the finishing machine drive motor (not shown) connected with one of the other wheels. It will thus be seen that the contact wheel 10 rotates with respect to the mounting arm 12 due to the driving force of the abrasive belt 14.

In a finishing operation, the drive motor is started and places the belt 14, the contact wheel 10 and the other guide wheels on the frame in motion. The external abrasive face of the belt 14 on the segment passing over the contact wheel 10 is then placed in contact with the workpiece to be finished by the operator who holds the workpiece manually or in a jig.

As can be seen in FIGS. 1, 2, and 3, the contact wheel 10 is composed principally of an external tread 16 and an internal support sleeve 18 on which the tread is mounted. It is common in the manufacture of such contact wheels to cement or bond the resilient tread 16 to the sleeve 18 along the cylindrical interface formed by the inner surface 20 of the tread l6 and the mating outer surface 22 of the sleeve 18. Heat generated during the finishing operation tends to weaken or destroy the bond or it can cause the tread to disintegrate.

The tread 16 is formed from a resilient material, such as a vinyl rubber, and is supplied in a variety of sizes and degrees of hardness or resilience for different fin ishing operations. In addition, the tread is frequently provided with helical or other serrations on the peripheral surface which vary the compliance of the tread, improve adhesion between the belt and contact wheel and offer a limited amount of cooling.

The sleeve 18, usually composed of a light-weight metal, forms a relatively rigid supporting annulus for the more pliable tread 16 and the tread serves as a com pliant base on which the abrasive belt 14 runs. The compliance of the tread 16 permits the belt 14 to conform to the contours of the workpiece being worked on and allows workpieces having regular configurations to be polished or finished without goughing or damaging the general shape of the workpiece.

In accordance with the present invention, the sleeve 18 forms a portion of a contact wheel hub assembly which is provided with a fluid cooling arrangement to remove heat from the contact wheel 10 during a finishing operation. As seen most clearly in the sectional view in FIG. 3, the annular sleeve 18 is mounted coaxially on a stationary support shaft 30 by means of two sealed'journal bearings 32 and 34 for rotation about the axis of the sleeve. To hold the bearings at axially spaced stations on the support shaft 30, the inner surface of the sleeve 18 is recessed slightly at each axial end of the sleeve to form shoulders 36 and 38 against which the outer races of the bearings 32 and 34 rest. The spaced bearings 32 and 34 are located axially on the shaft 30 by means of a washer 40 and a nut 42 threaded onto one end of the shaft 30 and a flange 44 forming an integral part of the shaft 30 at the other end. The flange 44 bears a pair of flats 46 and 48 for a wrench and the adjacent end of the shaft 30 is threaded so that it can be mounted in cantilever fashion, as shown in FIG. 4, in a threaded aperture at the projecting end of the support arm 12.

Cooling fluid conduits are provided in the support arm 12, the shaft 30 and the sleeve 18 so that a cooling fluid, such as air, can flow through the contact wheel in close proximity to the interface of the tread l6 and sleeve 18. As seen most clearly in FIG. 4, the support arm 12 has a drilled passageway 50 extending from an air fitting 52 to the threaded aperture of the arm 12 in which the shaft 30 is mounted. The end of the passageway at the projecting end of the arm 12 is closed by means of a plug 54.

The cooling fluid is delivered to the fitting 52 through a supply hose 56 at a controlled pressure to regulate the flow rate and flows through the passageway 50 and then into the shaft 30 which is also provided with a fluid passageway 60 (FIGS. 3 and 4). The passageway 60 is closed at one end by a plug 62 and extends from four fluid supply ports 64 in an annular recess 66 of the shaft 30 to four exit ports 68 at an axial station of the shaft 30 intermediate the two sealed journal bearings 32 and 34.

The sleeve 18 includes a plurality of grooves 70, 72, 74 and 76 extending axially along the inner surface of the sleeve from one axial end face to the other. The outer races of the bearings 32 and 34 are mounted in close fitting contact with the recesses at the ends of the sleeve and cooperate with the grooves 70, 72, 74 and 76 to form small passageways at the axial ends of the sleeve 18. It will be understood that the sealed bearings form an annular chamber 80 within the sleeve 18 and around the central portion of the mounting shaft 30 containing the fluid ports 68 and cause fluid moving through passageways 50 and 60 and chamber 80 to pass through the grooves 70, 72, 74 and 76 to the ambient environment. As the fluid passes from the chamber 80 through the grooves, it acquires heat transferred to the sleeve 18 from the tread 16 during a finishing operation and removes that heat from the contact wheel 10. Since the grooves 70, 72, 74 and 76 are in close proximity to the interface between the tread 16 and sleeve 18, the temperature at that interface is reduced from that which would otherwise exist in the absence of the grooves. By lowering the temperature at the interface, damage to or destruction of the joint at the interface or to the tread and the chances for a failure are reduced. In addition to prolonging the life of the contact wheel 10, the cooling fluid also reduces the operating temperature of the bearings 32 and 34 and in this manner prolongs the life of the bearings.

I claim:

l. A fluid cooled hub assembly adapted for mounting the resilient tread ofa contact wheel including: a rotatable support member having a generally cylindrical outer tread mounting surface and a coaxial inner surface, both the inner and outer surfaces extending coaxially with the axis of rotation of said member and a cooling fluid conduit defined by a groove extending in the axial direction along at least one portion of said inner surface beneath the outer tread mounting surface.

2. A fluid cooled hub assembly as defined in claim 1 wherein the rotatable support member has an axial end face at one end, the inner and outer surfaces of the member extending axially of the member to the axial end face; and the inner surface has a plurality of the grooves extending axially of the member to the axial end face to define a plurality of the cooling fluid conduits.

3. A fluid cooled hub assembly as defined in claim 1 wherein said rotatable support member is a support sleeve; and wherein a mounting shaft extends coaxially within said support sleeve and a plurality of axially spaced journal bearings are interposed between said mounting shaft and said support sleeve, said mounting shaft having a cooling fluid conduit extending axially along at least a portion of its length and at least one generally radial port extending therefrom to provide communication between its conduit and the grooves in said support sleeve between said bearings.

4. A fluid cooled hub assembly as defined in claim 3 further comprising a hub support arm having a mounting aperture for said mounting shaft and a cooling fluid conduit opening into the mounting aperture, said mounting shaft being positioned in the mounting aperture and having a port interconnecting the cooling fluid conduits of said shaft and said arm.

5. A fluid cooled contact wheel assembly comprising: a rotatable support sleeve having an external tread mounting surface and a generally cylindrical internal surface defining a plurality of fluid conducting grooves extending axially along the sleeve; an annular tread member formed from a resilient material mounted to the external tread mounting surface of the support sleeve; a support shaft extending coaxially within the support sleeve and having a cooling fluid conduit extending from one end portion of the shaft to a radial port exposed to the axially extending grooves on the internal surface of the sleeve; and a plurality of journal bearings interposed between the support shaft and support sleeve and axially spaced along the shaft at opposite sides of the radial port.

6. The fluid cooled contact wheel assembly according to claim 5 further including a support arm having the fluid conduit of the arm at the mounting aperture. 

1. A fluid cooled hub assembly adapted for mounting the resilient tread of a contact wheel including: a rotatable support member having a generally cylindrical outer tread mounting surface and a coaxial inner surface, both the inner and outer surfaces extending coaxially with the axis of rotation of said member and a cooling fluid conduit defined by a groove extending in the axial direction along at least one portion of said inner surface beneath the outer tread mounting surface.
 2. A fluid cooled hub assembly as defined in claim 1 wherein the rotatable support member has an axial end face at one end, the inner and outer surfaces of the member extending axially of the member to the axial end face; and the inner surface has a plurality of the grooves extending axially of the member to the axial end face to define a plurality of the cooling fluid conduits.
 3. A fluid cooled hub assembly as defined in claim 1 wherein said rotatable support member is a support sleeve; and wherein a mounting shaft extends coaxially within said support sleeve and a plurality of axially spaced Journal bearings are interposed between said mounting shaft and said support sleeve, said mounting shaft having a cooling fluid conduit extending axially along at least a portion of its length and at least one generally radial port extending therefrom to provide communication between its conduit and the grooves in said support sleeve between said bearings.
 4. A fluid cooled hub assembly as defined in claim 3 further comprising a hub support arm having a mounting aperture for said mounting shaft and a cooling fluid conduit opening into the mounting aperture, said mounting shaft being positioned in the mounting aperture and having a port interconnecting the cooling fluid conduits of said shaft and said arm.
 5. A fluid cooled contact wheel assembly comprising: a rotatable support sleeve having an external tread mounting surface and a generally cylindrical internal surface defining a plurality of fluid conducting grooves extending axially along the sleeve; an annular tread member formed from a resilient material mounted to the external tread mounting surface of the support sleeve; a support shaft extending coaxially within the support sleeve and having a cooling fluid conduit extending from one end portion of the shaft to a radial port exposed to the axially extending grooves on the internal surface of the sleeve; and a plurality of journal bearings interposed between the support shaft and support sleeve and axially spaced along the shaft at opposite sides of the radial port.
 6. The fluid cooled contact wheel assembly according to claim 5 further including a support arm having a mounting aperture accommodating said one end portion of the support shaft and a cooling fluid conduit extending along the arm to the mounting aperture, said one end portion of the support shaft having fluid porting communicating the fluid conduit of the shaft with the fluid conduit of the arm at the mounting aperture. 